In a field of pharmaceutical development, study and the like, a storage and a transfer have been carried out by sealing a sample-solved solution into a vessel called a microtube having an upper part and a lower part. The upper part is larger in outline than the lower part. A plurality of the microtubes stand vertically in a storage rack, defined as a grid shape, for example a storage rack defined into 96 in 8 rows and 12 columns (hereinafter referred to as “96 tube racks”) to accommodate them. Further, a storage rack having a total defined number of 384 microtube in 16 rows and 24 columns (hereinafter referred to as “384 tube racks”) has been also known to accommodate smaller microtube.
As a microtube picking device for pharmaceutical development for taking a selected microtube out of or into such a 96 tube racks or 384 tube racks, a microtube picking device 500 for pharmaceutical development as shown in FIG. 9 has been known. This microtube picking device 500 for pharmaceutical development has insertion holes 532, into which the microtube are loosely supported. The insertion holes have a cross section smaller than the upper parts and larger than the lower parts of the microtube which fit to a lower part of the microtube 510 to support the microtube, and are formed in a storage rack 530. The picking device 500 has a plunger member 540 which may be protruded to displace a selected microtube 510 directly above through the insertion hole 532 of the storage rack 530 by abutting the bottom surface of the microtube 510. The plunger member is at a lower position than the storage rack 530, and a concurrently-lifting prevention member 560 is positioned above the top surfaces of the surrounding microtube so that the microtube pushed up with the plunger member 540 does not lift the surrounding microtube together exists at upper position than microtube 510. The microtube picking device 500 has opposed gripping members 522, which provide a space slightly smaller in size than the size of the upper part of the protruded up microtube 510 and sandwich the microtube between the opposed gripping members to grip the microtube 510 which was advanced in accordance with a protrusion-up operation by the plunger member 540 under the microtube 510 by allowing the space between the resilient gripping members 522 to be narrowed to accommodate the microtube. The microtube picking device 500 also has a dispensing plunger member 550, which discharges the microtube 510 gripped by the picking member 520. The material of a resilient gripping members 522 is preferably a plastic such as polypropylene having sufficient elastic force at a very low temperature to grip the microtube. (See FIG. 1 of Japanese Laid-Open Patent Publication No. 2006-214919)
It is generally the practice, when using the 384 tube racks, to form a closure on the microtube by fusion-welding an aluminum foil to an opening portion of the top of the microtube. A small tab portion of the aluminum foil is extended beyond a wall of the opening of the microtube. Thus there is a problem that the tab portion causes friction to occur with the resilient gripping member 522.
Further, since the gripping members 522 are provided on both sides of the microtube 510 and are deflected, unbalance occurs in the respective amounts of deflections of the members 522 and the microtube become off-center and the position of the microtube 510 is not kept properly centered. Thus since the position of the microtube 510 is shifted, the microtube 510 cannot be re-inserted into the storage rack 530.
Further, since the sandwich directions of the gripping members 522 are directed to opposed two surfaces, the microtube sometimes is inclined to a direction perpendicular to the surfaces. As a result a phenomenon that the microtube 510 cannot be re-inserted into the storage rack 530 occurs.